To the Editor: I am concerned about a potential
confounder in the randomized controlled trial by the initial Heart Outcomes
Prevention Evaluation (HOPE) and HOPE−The Ongoing Outcomes (HOPE-TOO)
trial investigators1 on long-term vitamin E
supplementation and cardiovascular events and cancer. There was no presentation
of the prevalence of glitazone use in both treatment groups, whether this
variable was controlled for in the data analysis, or whether the patients
who developed new-onset heart failure had been taking glitazone drugs. Similarly,
a breakdown of the percentage of patients from the United States, Canada,
and Brazil, in which these drugs were marketed differently, would have been
helpful.